1. Field of the Invention
The present invention relates to an inkjet print head and a method for making the same. More specifically, the present invention relates to an inkjet print head that uses an adhesive sheet to contribute to improved yield in inkjet print head production.
2. Description of the Related Art
In the inkjet print head field, the nozzle pitch of an inkjet print head has been decreasing year by year, leading to a demand for high-precision processing technology.
In the assembly of ink channel forming plates in the ink channel unit of the head, a well-known method uses adhesives. In many cases, the adhesive is an epoxy adhesive. However, if an epoxy resin with a low molecular weight is used as the adhesive on an entire surface, the adhesive may spread into ink channels when a pressure is applied for adhesion in the assemble process.
Thus, to limit the spreading out of the adhesive, a thickness of the adhesive agent must be controlled.
Japanese Laid-Open Patent Publication Number 11-10864 discloses a method in which a filler is dispersed in the adhesive agent to serve as a spacer. As such, the filler diameter must be small in order to provide a uniform coating. However, smaller diameters reduce the effectiveness of fillers as spacers. Thus, establishing optimal conditions in the production of an inkjet print head using adhesives is difficult.
In view of the foregoing and other problems, drawbacks, and disadvantages of the conventional methods and structures, an object of the present invention is to provide an easily reproducible method for heating and pressurizing multiple inkjet channel forming plates during a process of forming ink channel units in inkjet print heads, and to provide an inkjet print head with uniform ink jetting characteristics.
Another object of the present invention is to provide an adhesive agent that eliminates or reproducibly controls the spreading out of an adhesive agent to an ink channel when adhesion is performed by applying heat and pressure.
In a first aspect of the invention, an inkjet print head with an ink channel unit is provided. The inkjet head includes a plurality of plates and an adhesive sheet for adhering together the plurality of plates. The adhesive sheet includes an adhesive element dispersed in a polymer matrix. The polymer matrix includes a resin.
According to another aspect of the invention, a cross-linking agent is added to the polymer matrix.
According to another aspect of the invention, the polymer matrix is formed from an epoxy resin with an average molecular weight of at least about 50000 amu.
According to another aspect of the invention, a curing temperature of an adhesive element in the adhesive sheet is lower than a curing temperature of the polymer matrix. The adhesive agent is prepared using an epoxy resin having a low average molecular weight of no more than about 10000 amu.
According to another aspect of the invention, a ratio of the adhesive element to the polymer matrix is within a range of about 1% to about 60% by solids content weight.
According to another aspect of the invention, the adhesive sheet has a thickness of about 1 micron to about 10 microns.
Additionally, in accordance with another aspect of the invention, a method for making an inkjet print head equipped with an ink channel unit is provided. The method includes forming an opening matching a channel pattern of a first plate in an adhesive sheet with a carrier sheet, performing a preliminary adhesion by setting the adhesive sheet to the first plate in alignment with the channel pattern, peeling away the carrier sheet on the adhesive sheet, and laminating a second plate on the adhesive sheet and applying heat and/or pressure to adhere the second plate to the first plate.
According to another aspect of the invention, an ink channel for an inkjet print head includes first and second plates, an adhesive sheet including an adhesive element and a polymer matrix, the adhesive element having a melting and curing temperature lower than that of the polymer matrix.
According to another aspect of the invention, a method of forming an ink channel unit includes adhering together first and second plates with an adhesive sheet having an adhesive element and a polymer matrix. The adhesive element having a melting and curing temperature lower than that of the polymer matrix.
Further, according to another aspect of the invention, a method of forming an ink channel unit includes measuring a high temperature strength of a polymer matrix in an adhesive sheet. Then, based on the measuring, reproducibly controlling a thickness of the adhesive sheet is gained for forming the adhesive sheet on one of first and second plates to adhere the first and second plates together.
In an exemplary embodiment of the present invention, a matrix is formed from a straight-chain macromolecule that can be formed as a sheet. An adhesive element having a low molecular weight is dispersed in this matrix. An adhesive agent sheet can adhere an adhesion module (e.g., plate) with an adhesive element that seeps out while maintaining a particular thickness for the adhesive layer even in heating and pressurizing processes. As a result, spreading of the adhesive agent into ink channels can be reproducibly controlled.
With the unique and unobvious aspects and exemplary embodiments of the invention, the specific mechanism by which adhesion takes place is controlled. In this manner, the present invention is able to provide advantages including an optimal spreading out of an adhesive agent into ink channels and an adhesive method having good reproducibility. Thus, an inkjet head with uniform ink jetting characteristics may be provided.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 2001-321582, filed on Oct. 19, 2001, and Japanese Patent Application No. 2002-244722, filed on Aug. 26, 2002 which are expressly incorporated herein by reference in their entirety.